High-rise buildings typically contain a number of elevators, escalators and other corresponding traveling means for transporting people from one floor to another in the building. When passengers on the floor levels give calls to the elevators, the group control of the elevator group allocates elevator cars for the use of the passengers on the basis of the desired optimization criteria. The giving of calls in a conventional elevator system is arranged by disposing up/down pushbuttons on each floor level, by means of which a passenger expresses his/her desired direction of travel and further, after the elevator car has reached the floor level on which the passenger is located, the passenger expresses in the elevator car his/her desired destination floor level by means of the destination floor pushbuttons in the elevator car. The method of giving calls described above is, however, impractical and often inefficient, as a result of which the giving of calls in elevator systems is implemented to an increasing extent by means of so-called destination call systems, in which each passenger expresses his/her personal destination floor already at the departure floor, e.g. in the entrance lobby before going into the elevator car. The giving of a destination call takes place by means of a special destination call terminal, either with pushbuttons or by means of an electrically readable identifier, e.g. an RFID (radio frequency identifier) tag. Since in connection with a destination call the departure point and terminal point of the travel route of each passenger is identified and therefore available to the group control, the group control is able to determine the travel route of a passenger precisely and optimally compared to a conventional call-giving system.
In large building complexes passengers are generally served by more than one elevator group. Often an elevator system is implemented in such a way that a passenger gets to the destination floor he/she wants using only a certain elevator group, in which case the elevator passenger must have advance information about which floors each elevator group serves and must give at the departure floor an elevator call to exactly the correct elevator group in order to get to the destination floor. Finding the correct elevator group can, however, be awkward especially in large buildings, causing uncertainty in the passenger when choosing the correct travel route. On the other hand, if a passenger has available for use a number of elevator groups for getting to the destination floor he/she wants, one problem that can arise is that the passenger does not have any information about the degree of loading of the different elevator groups, in which case he/she can choose a more congested elevator group instead of choosing an uncongested elevator group that would probably serve him/her more quickly.
One possible way to solve the problems described above is to combine the elevator groups and to implement the whole elevator system as one elevator group, in which the allocation of calls occurs in one group control. Efficient allocation of calls and all kinds of optimization of the traffic of the elevator group requires of the group control, however, computation of complex algorithms and therefore very efficient data processing ability if the number of elevators in the elevator group is great. In this case the group control becomes complicated and expensive compared to a simpler standard group control, which is optimized for control of a smaller elevator group comprising e.g. a maximum of 8 elevators.